U.S. patent application number 14/830909 was filed with the patent office on 2016-02-25 for landing gear assembly.
The applicant listed for this patent is Airbus Operations Limited. Invention is credited to Nicholas ELLIOTT.
Application Number | 20160052623 14/830909 |
Document ID | / |
Family ID | 51726977 |
Filed Date | 2016-02-25 |
United States Patent
Application |
20160052623 |
Kind Code |
A1 |
ELLIOTT; Nicholas |
February 25, 2016 |
LANDING GEAR ASSEMBLY
Abstract
The present invention provides a landing gear assembly for an
aircraft landing gear, the assembly comprising a steering mechanism
for steering at least one wheel of the landing gear, a deployment
mechanism for moving a leg of the landing gear between a stowed
position and a deployed position, and an actuator arranged to
actuate both the steering mechanism and the deployment mechanism.
The invention also provides an aircraft landing gear, an aircraft
and methods of operating an aircraft landing gear.
Inventors: |
ELLIOTT; Nicholas; (Bristol,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Airbus Operations Limited |
Bristol |
|
GB |
|
|
Family ID: |
51726977 |
Appl. No.: |
14/830909 |
Filed: |
August 20, 2015 |
Current U.S.
Class: |
244/102R |
Current CPC
Class: |
B64C 25/22 20130101;
B64C 25/34 20130101; B64C 25/50 20130101; B64C 25/18 20130101; B64C
25/14 20130101 |
International
Class: |
B64C 25/18 20060101
B64C025/18; B64C 25/34 20060101 B64C025/34; B64C 25/14 20060101
B64C025/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 22, 2014 |
GB |
1414986.8 |
Claims
1. A landing gear assembly for an aircraft landing gear, the
assembly comprising: a steering mechanism for steering at least one
wheel of the landing gear, a deployment mechanism for moving a leg
of the landing gear between a stowed position and a deployed
position, and an actuator arranged to actuate both the steering
mechanism and the deployment mechanism.
2. A landing gear assembly as claimed in claim 1, wherein the
landing gear assembly further comprises a coupling mechanism for
coupling the actuator to the steering mechanism and the deployment
mechanism, wherein the coupling mechanism is arranged to couple the
actuator to only one of the steering mechanism and the deployment
mechanism at any one time.
3. A landing gear assembly as claimed in claim 2, wherein the
coupling mechanism is arranged to automatically couple the actuator
to only one of the steering mechanism and the deployment mechanism
at any one time.
4. A landing gear assembly as claimed in claim 2, wherein the
coupling mechanism is arranged to couple the actuator to the
steering mechanism when the wheel is in a "weight on wheel"
situation and to couple the actuator to the deployment mechanism
when the wheel is in a "weight off wheel" situation.
5. A landing gear assembly as claimed in claim 4, wherein the
coupling mechanism comprises a locking mechanism, comprising a
locking element moveable between a steering locked position, in
which the steering mechanism is prevented from steering the wheel,
and a steering unlocked position, in which the steering mechanism
is able to steer the wheel, wherein when the wheel is in a "weight
on wheel" situation the locking element is moved to the steering
unlocked position and when the wheel is in a "weight off wheel"
situation, the locking element is moved to the steering locked
position.
6. A landing gear assembly as claimed in claim 5, wherein the
locking element moves from the steering locked position to the
steering unlocked position under the action of the wheel being
moved from a dropped position to a raised position relative to the
locking element when the wheel changes from a "weight off wheel" to
a "weight on wheel" situation and moves from the steering unlocked
position to the steering locked position under the action of the
wheel being moved from the raised position to the dropped position
relative to the locking element when the wheel changes from a
"weight on wheel" to a "weight off wheel" situation.
7. A landing gear assembly as claimed in claim 6, wherein the
coupling mechanism comprises a crank arm rotatable between first
and second rotation positions by the actuator when the locking
element is in the steering unlocked position, and prevented from
rotating when the locking element is in the steering locked
position.
8. A landing gear assembly as claimed in claim 7, wherein the crank
arm is connected to the steering mechanism such that when the crank
arm is in the first rotation position, the steering mechanism
steers the wheel in a first direction and when the crank arm is in
the second rotation position, the steering mechanism steers the
wheel in a second different direction.
9. A landing gear assembly as claimed in claim 8, wherein the crank
arm is connected to the steering mechanism by a bevel gear
arrangement such that rotational movement of the crank arm is
converted to rotational movement of the steering mechanism.
10. A landing gear assembly as claimed in claim 9, wherein, when in
the steering locked position, the locking element acts on the bevel
gear arrangement to prevent its rotation.
11. A landing gear assembly as claimed in any of claims 7 to 9
claim 7, wherein, when in the steering locked position, the locking
element acts on the steering mechanism to prevent its rotation.
12. A landing gear assembly as claimed in claim 11, wherein the
locking element is part of a centring arrangement for centring the
steering mechanism, such that the wheel is steered in a central
direction when the wheel is in a "weight off wheel" situation.
13. A landing gear assembly as claimed in claim 7, wherein the
coupling mechanism comprises a lever arm connected at its first end
to the actuator and moveable by the actuator between extended and
retracted positions.
14. A landing gear assembly as claimed in claim 13, wherein the
lever arm is rotatably connected at its second end to the crank arm
such that when the lever arm is caused to extend and retract by the
actuator, the crank arm is caused to rotate by the lever arm.
15. A landing gear assembly as claimed in claim 14, wherein, when
the crank arm is prevented from rotating by the locking element in
the steering locked position, movement by the actuator of the lever
arm between extended and retracted positions instead causes the
landing gear leg to move between the deployed and stowed
positions.
16. A landing gear assembly as claimed in claim 1, wherein the
steering mechanism comprises a steering collar connected to the
actuator and one or more torque links connected to the wheel.
17. A landing gear assembly as claimed in claim 1, wherein the
deployment mechanism comprises a number of moveable links,
including a lock link, connected between the actuator and the
landing gear leg.
18. A landing gear assembly as claimed in claim 17, wherein the
deployment mechanism further comprises a lock link actuator for
moving the lock link.
19. An aircraft landing gear comprising the landing gear
arrangement of claim 1.
20. An aircraft comprising the aircraft landing gear or the landing
gear arrangement of claim 1.
21. A method of operating an aircraft landing gear comprising the
step of providing a landing gear arrangement, aircraft landing gear
or aircraft of claim 1.
22. A method of operating an aircraft landing gear comprising the
steps of: i) in a first time period: placing a wheel of the landing
gear on the ground such that the wheel is in a "weight on wheel"
situation, thereby moving a steering locking element of the landing
gear to a steering unlocked position, and then using an actuator of
the landing gear to steer the wheel, and ii) in a second time
period: removing the wheel of the landing gear from the ground such
that the wheel is in a "weight off wheel" situation, thereby moving
the steering locking element to a steering locked position, and
then using the actuator to stow and/or deploy the landing gear.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention concerns a landing gear assembly for
an aircraft landing gear. More particularly, but not exclusively,
the present invention concerns a landing gear assembly comprising a
steering mechanism for steering at least one wheel of the landing
gear and a deployment mechanism for moving a leg of the landing
gear between a stowed position and a deployed position. The
invention also concerns an aircraft landing gear, an aircraft and
methods of operating an aircraft landing gear.
[0002] A typical prior art aircraft nose landing gear comprises a
steering mechanism for steering at least one wheel of the landing
gear and a deployment mechanism for moving a leg of the landing
gear between a stowed position and a deployed position. Each of the
mechanisms has an actuator associated with it to actuate the
mechanism. The steering actuator actuates the steering mechanism to
steer the at least one wheel. The deployment actuator actuates the
deployment mechanism, including a foldable drag stay, to deploy or
stow the landing gear. The deployment mechanism also typically
comprises an uplock link for preventing the drag stay from folding
when the landing gear leg is in the deployed position. The uplock
link functions as a two-part linkage with an over-centre hinge, to
lock it in place. There is also typically an uplock actuator that
moves the uplock out of a locking position when the leg is to be
moved to the stowed position. A typical prior art aircraft nose
landing gear also comprises a centreing cam arrangement. This
centreing cam arrangement ensures that a wheel of the landing gear
is centred--i.e. orientated in a straight direction (in an
orientation so that the aircraft would not be steered left or
right, off its course--i.e. when the wheel is substantially
parallel to the aircraft centre line) when in a "weight off wheel"
situation. This means that when the landing gear is deployed and
the aircraft then lands, the aircraft is not accidentally steered
off course.
[0003] There is a desire to make landing gears as light as possible
to reduce fuel burn, whilst still providing the required
functionality and safety. The prior art landing gears may be
considered to be heavier than desired.
[0004] The present invention seeks to mitigate the above-mentioned
problems. Alternatively or additionally, the present invention
seeks to provide an improved landing gear assembly for an aircraft
landing gear.
SUMMARY OF THE INVENTION
[0005] The present invention provides, according to a first aspect,
a landing gear assembly for an aircraft landing gear, the assembly
comprising a steering mechanism for steering at least one wheel of
the landing gear, a deployment mechanism for moving a leg of the
landing gear between a stowed position and a deployed position, and
an actuator arranged to actuate both the steering mechanism and the
deployment mechanism.
[0006] The inventor has realised that the same actuator could be
used for actuating both the steering mechanism and the deployment
mechanism. In particular, it is noted that, when the aircraft is to
be steered by the landing gear (when it is in a "weight on wheel"
situation), the landing gear is always deployed, and when the
landing gear is stowed, or being moved to be stowed, (when it is in
a "weight off wheel" situation) the aircraft does not need to be
steered by the landing gear. Having one actuator (and associated
systems and pipework) instead of two, reduces the weight of the
landing gear assembly, and thus decreases fuel burn of the
aircraft. It also reduces the maintenance burden and reduces the
drag and noise generated by the landing gear assembly, when the
landing gear leg is deployed.
[0007] The present invention provides a landing gear assembly for
an aircraft landing gear, the assembly comprising a steering
mechanism for steering at least one wheel of the landing gear, a
deployment mechanism for moving a leg of the landing gear between a
stowed position and a deployed position, and a single actuator
arranged to actuate both the steering mechanism and the deployment
mechanism.
[0008] The landing gear assembly is preferably for an aircraft nose
landing gear.
[0009] Preferably, the landing gear assembly further comprises a
coupling mechanism for coupling the actuator to the steering
mechanism and the deployment mechanism, wherein the coupling
mechanism is arranged to couple the actuator to only one of the
steering mechanism and the deployment mechanism at any one time.
This ensures that the actuator can be coupled to only the
appropriate mechanism in each appropriate situation.
[0010] The coupling mechanism is arranged to couple the actuator to
each respective mechanism such that the respective mechanism is
able to be actuated by the actuator. The coupling mechanism may do
this by connecting the respective mechanism to the actuator.
However, preferably, the coupling mechanism does this by preventing
the other mechanism from being actuated by the actuator.
[0011] Preferably, the coupling mechanism is arranged to
automatically couple the actuator to only one of the steering
mechanism and the deployment mechanism at any one time. The
automatic coupling is preferably achieved by mechanical action of
the coupling mechanism.
[0012] Preferably, the landing gear assembly further comprises a
coupling mechanism for coupling the actuator to the steering
mechanism and the deployment mechanism, wherein the coupling
mechanism is arranged to automatically couple (preferably by a
mechanical action of the coupling mechanism) the actuator to only
one of the steering mechanism and the deployment mechanism at any
one time.
[0013] More preferably, the coupling mechanism is arranged to
couple the actuator to the steering mechanism when the wheel is in
a "weight on wheel" situation and to couple the actuator to the
deployment mechanism when the wheel is in a "weight off wheel"
situation. This ensures that the steering mechanism can be actuated
when it is needed and the deployment mechanism can be actuated when
it is needed.
[0014] More preferably, the coupling mechanism is arranged to
automatically couple the actuator to the steering mechanism when
the wheel is in a "weight on wheel" situation and to automatically
couple the actuator to the deployment mechanism when the wheel is
in a "weight off wheel" situation. The automatic coupling is
preferably achieved by mechanical action of the coupling
mechanism.
[0015] A "weight on wheel" situation is one in which the at least
one wheel would be touching the ground and supporting at least a
first amount of the weight of the aircraft. A "weight off wheel"
situation is one in which the at least one wheel would be
supporting less than the first amount of weight of the aircraft and
the wheel is often not touching the ground. The first amount may be
very small and may be zero or close to zero.
[0016] The automatic coupling of the coupling mechanism is
preferably achieved by a mechanical action of the coupling
mechanism as a result of a change between a "weight on wheel" and a
"weight off wheel" situation.
[0017] Even more preferably, the coupling mechanism comprises a
locking mechanism, comprising a locking element moveable between a
steering locked position, in which the steering mechanism is
prevented from steering the wheel, and a steering unlocked
position, in which the steering mechanism is able to steer the
wheel, wherein when the wheel is in a "weight on wheel" situation
the locking element is (automatically) moved to the steering
unlocked position and when the wheel is in a "weight off wheel"
situation, the locking element is (automatically) moved to the
steering locked position. This allows the "switch" between the
mechanisms by the coupling mechanism to be provided by the locking
mechanism.
[0018] Even more preferably, the locking element (automatically)
moves from the steering locked position to the steering unlocked
position under the action of the wheel being moved from a dropped
position to a raised position relative to the locking element when
the wheel changes from a "weight off wheel" to a "weight on wheel"
situation and (automatically) moves from the steering unlocked
position to the steering locked position under the action of the
wheel being moved from the raised position to the dropped position
relative to the locking element when the wheel changes from a
"weight on wheel" to a "weight off wheel" situation. This allows
the "switch" between the mechanisms by the coupling mechanism to be
"automatic", without user/pilot input being required.
[0019] The coupling mechanism may be arranged to convert linear
motion of the actuator to rotational motion, in order to rotate a
part of the steering mechanism.
[0020] Even more preferably, the coupling mechanism comprises a
crank arm rotatable between first and second rotation positions by
the actuator when the locking element is in the steering unlocked
position, and prevented from rotating when the locking element is
in the steering locked position. The crank arm being prevented from
rotating provides that steering of the at least one wheel can be
prevented.
[0021] Even more preferably, the crank arm is connected to the
steering mechanism such that when the crank arm is in the first
rotation position, the steering mechanism steers the wheel in a
first direction and when the crank arm is in the second rotation
position, the steering mechanism steers the wheel in a second
different direction. This allows the rotation of the crank arm to
enable steering of the at least one wheel.
[0022] Even more preferably, the crank arm is connected to the
steering mechanism by a bevel gear arrangement such that rotational
movement of the crank arm is converted to rotational movement of
the steering mechanism.
[0023] Preferably, when in the steering locked position, the
locking element acts on the bevel gear arrangement to prevent its
rotation.
[0024] Additionally or alternatively, when in the steering locked
position, the locking element acts on the steering mechanism to
prevent its rotation.
[0025] The locking mechanism may comprise two or more locking
elements; a first locking element may act on the bevel gear
arrangement to prevent its rotation, and a second locking element
may act on the steering mechanism to prevent its rotation.
[0026] Preferably, the locking element is part of a centring
arrangement for centring the steering mechanism, such that the
wheel is steered in a central direction (i.e. when the at least one
wheel is centred--i.e. orientated in a straight direction (in an
orientation so that the aircraft would not be steered left or
right, off its course) when the wheel is in a "weight off wheel"
situation. This means that when the landing gear is deployed and
the aircraft then lands, the aircraft is not accidentally steered
off course.
[0027] Preferably, the coupling mechanism comprises a lever arm
connected at its first end to the actuator and moveable by the
actuator between extended and retracted positions.
[0028] Even more preferably, the lever arm is rotatably connected
at its second end to the crank arm such that when the lever arm is
caused to extend and retract by the actuator, the crank arm is
caused to rotate by the lever arm.
[0029] Even more preferably, when the crank arm is prevented from
rotating by the locking element in the steering locked position,
movement by the actuator of the lever arm between extended and
retracted positions instead causes the landing gear leg to move
between the deployed and stowed positions.
[0030] Preferably, the steering mechanism comprises a steering
collar connected to the actuator and one or more torque links
connected to the wheel.
[0031] Preferably, the deployment mechanism comprises a number of
moveable links, including a lock link, connected between the
actuator and the landing gear leg.
[0032] More preferably, the deployment mechanism further comprises
a lock link actuator for moving the lock link.
[0033] According to a second aspect of the invention there is also
provided an aircraft landing gear comprising the landing gear
arrangement of the first aspect of the invention. The aircraft
landing gear is preferably an aircraft nose landing gear.
[0034] According to a third aspect of the invention there is also
provided an aircraft comprising the aircraft landing gear of the
second aspect of the invention or the landing gear arrangement of
the first aspect of the invention.
[0035] According to a fourth aspect of the invention there is also
provided a method of operating an aircraft landing gear comprising
the step of providing a landing gear arrangement, aircraft landing
gear or aircraft of the first, second or third aspect of the
invention.
[0036] According to a fifth aspect of the invention there is also
provided a method of operating an aircraft landing gear comprising
the steps of, in a first time period, placing a wheel of the
landing gear on the ground such that the wheel is in a "weight on
wheel" situation, thereby moving a steering locking element of the
landing gear to a steering unlocked position (in which the steering
mechanism is able to steer the wheel), and then using an actuator
of the landing gear to steer the wheel, and, in a second time
period, removing the wheel of the landing gear from the ground such
that the wheel is in a "weight off wheel" situation, thereby moving
the steering locking element to a steering locked position (in
which the steering mechanism is prevented from steering the wheel),
and then using the actuator to stow and/or deploy the landing
gear.
[0037] According to a fifth aspect of the invention there is also
provided a method of operating an aircraft landing gear comprising
the steps of, in a first time period, placing a wheel of the
landing gear on the ground such that the wheel is in a "weight on
wheel" situation, thereby moving a steering locking element of the
landing gear to a steering unlocked position (in which the steering
mechanism is able to steer the wheel), and then using an actuator
of the landing gear to steer the wheel, and, in a second time
period, removing the wheel of the landing gear from the ground such
that the wheel is in a "weight off wheel" situation, thereby moving
the steering locking element to a steering locked position (in
which the steering mechanism is prevented from steering the wheel),
and then using the same actuator to stow and/or deploy the landing
gear.
[0038] Preferably, the aircraft landing gear is an aircraft nose
landing gear.
[0039] It will of course be appreciated that features described in
relation to one aspect of the present invention may be incorporated
into other aspects of the present invention. For example, the
method of the invention may incorporate any of the features
described with reference to the apparatus of the invention and vice
versa.
DESCRIPTION OF THE DRAWINGS
[0040] Embodiments of the present invention will now be described
by way of example only with reference to the accompanying schematic
drawings of which:
[0041] FIG. 1 shows a side view of an aircraft nose landing gear
according to a first embodiment of the invention, in a deployed
"weight on wheel" situation;
[0042] FIG. 2 shows a side view of the aircraft nose landing gear,
in a deployed "weight off wheel" situation;
[0043] FIG. 3 shows a side view of the aircraft nose landing gear
being moved into a stowed position;
[0044] FIG. 4a shows a side view of part of the aircraft nose
landing gear in a deployed "weight on wheel" situation, whilst the
wheel is being steered left;
[0045] FIG. 4b shows a side view of part of the aircraft nose
landing gear in a deployed "weight on wheel" situation, whilst the
wheel is being steered centrally;
[0046] FIG. 4c shows a side view of part of the aircraft nose
landing gear in a deployed "weight on wheel" situation, whilst the
wheel is being steered right;
[0047] FIG. 5 shows a perspective view of a centreing cam
arrangement of the aircraft nose landing gear in a "weight on
wheel" situation;
[0048] FIG. 6a shows a side view of part of an aircraft nose
landing gear according to a second embodiment of the invention in a
"weight off wheel" situation;
[0049] FIG. 6b shows a side view of part of the aircraft nose
landing gear of FIG. 6a in a "weight on wheel" situation; and
[0050] FIG. 7 shows a front view of an aircraft, including the
aircraft nose landing gear of either the first or second
embodiment.
DETAILED DESCRIPTION
[0051] FIG. 1 shows a side view of an aircraft nose landing gear
500 according to a first embodiment of the invention, in a deployed
"weight on wheel" situation and FIG. 2 shows a side view of the
aircraft nose landing gear 500, in a deployed "weight off wheel"
situation. The forwards direction 701 is shown. In addition, the
ground surface 700 is also shown.
[0052] The landing gear 500 comprises a landing gear leg 501, which
is suspended from a fuselage 100 of an aircraft by a pivot point
506.
[0053] In addition, an actuator 530 is also suspended from the
fuselage 100 by a pivot point 531 behind the leg pivot point 506.
The actuator 530 itself will be explained in more detail in
relation to FIGS. 4a to 4c. The actuator 530 is attached to the
landing gear leg 501, by a lever arm 532 (acting as an actuator
rod), pivotally connected at pivot point 534 to a crank arm 533.
The crank arm 533 is pivotally connected to a bevel gear 515
located in the upper portion 505 of the landing gear leg 501.
[0054] In the "weight on wheel" situation of FIG. 1, the bevel gear
515 is located adjacent a steering disc 513 of a steering mechanism
510. The steering disc 513 connected to a steering column 514. The
steering column 514 is rotatably housed in the landing gear leg
501. Hence, pivotal movement of the crank arm 533 causes rotation
of the bevel gear 515 which causes rotation of the steering disc
513 and steering column 514. The steering column 514 is connected
to a first torque link 512 at a lower portion 504 of the landing
gear leg 501. The first torque link 512 is pivotally connected to a
second torque link 511 and that second torque link 511 is connected
to a wheel 502 of the landing gear leg 501 at an axle 503. Hence,
rotation of the steering column 514 causes, through the torque
links 511, 512, steering of the wheel 502.
[0055] The wheel 502 is supported by a wheel strut 541 which
extends upwards through the landing gear leg 501 and is slidably
mounted in the steering column 514. When in the "weight on wheel"
situation of FIG. 1, the wheel 502 and wheel strut 541 slide
upwards in relation to the landing gear leg 501 and steering column
514. When in the "weight off wheel" situation of FIG. 2, the wheel
502 and wheel strut 514 slide downwards in relation to the landing
gear leg 501 and steering column 514.
[0056] The wheel strut 541 and steering column 514 are linked by a
centreing cam arrangement (schematically shown as 542), which will
be described in more detail in relation to FIG. 5.
[0057] The landing gear 500 also comprises a deployment mechanism
520 comprising a two-part drag strut, comprising an upper part 521
pivotally connected at pivot point 525b to a lower part 522. The
upper end of the upper drag strut 521 is suspended from the
fuselage 100 at a pivot point 525a behind the actuator pivot point
531. The lower end of the lower drag strut 522 is pivotally
connected to an upper portion 505 of the landing gear leg 501 by
pivot point 525c. The deployment mechanism 520 also comprises a
two-part uplock, comprising a back part 524 and a front part 523.
The front end of the front part 523 is pivotally connected to the
drag strut near (or at the same point) as the pivot point 525b, at
pivot point 526a. The back 524 and front 523 parts are pivotally
connected to each other at pivot point 526b and the back end of
back part 524 is pivotally attached to the upper portion 505 of the
landing gear leg 501 by pivot point 526c, above pivot point
525c.
[0058] The "over-centre" uplock 523, 524 is used to lock the drag
strut 521, 522 in the deployed position shown in FIGS. 1 and 2.
Also present, but not shown in the figures, is a second actuator
used to move the uplock past the "over-centre" point to allow the
drag strut 521, 522 to move to stow the landing gear leg 501. The
stowing of the landing gear leg 501 will be described in more
detail, in relation to FIG. 3.
[0059] FIG. 4a shows a side view of part of the aircraft nose
landing gear 500 in a deployed "weight on wheel" situation, whilst
the wheel 502 is being steered left. Here, the actuator 530 can be
seen more clearly. It comprises an actuator block 537 fixed on an
actuator rod (the lever arm 532). The block 537 is contained within
an actuator chamber 538 of the actuator 530. Hence, actuation of
the actuator 530 moves the block 537 along the length of the
actuator chamber 538 and thus effectively increases and decreases
the length of the lever arm 532 extending from the actuator 530. In
FIG. 4a, the actuator block 537 is located at the upper end of the
actuator chamber 538 and hence a relatively large length of the
lever arm 532 has been pulled within the actuator 530. This means
that the effective (protruding) length of the lever arm 532 is
small. This causes the lever arm 523 to pull on the crank arm 533
and, by pivot point 534, rotate the crank arm 533 in an
anti-clockwise direction (as shown in FIG. 4a). This causes the
bevel gear 515 to also rotate anti-clockwise. This then causes the
steering disc 513 to rotate from left to right (as shown in FIG.
4a--i.e. anti-clockwise if viewed from the top of FIG. 4a) and
cause the steering column 514 to also rotate in that direction.
This then causes the torque links 511, 512 to rotate the wheel 502
so that it is steered in a left direction.
[0060] FIG. 4b shows a side view of part of the aircraft nose
landing gear in a deployed "weight on wheel" situation, whilst the
wheel is being steered centrally. Here, the actuator block 537 is
located substantially centrally in the actuator chamber 538. The
lever arm 532 has been effectively lengthened from FIG. 4a, and
therefore crank arm 533 and bevel gear 515 have been pivoted
clockwise. This rotates the steering disc 513 and steering column
514 to rotate towards the right and also causes the torque links
511, 512 to change the direction of the wheel 502 so that it is
being steered in a central direction.
[0061] FIG. 4c shows a side view of part of the aircraft nose
landing gear in a deployed "weight on wheel" situation, whilst the
wheel is being steered right. Here, the actuator block 537 has been
moved further down the actuator chamber 538 to a lower end of it.
The lever arm 532 has been effectively lengthened further from FIG.
4b, and therefore crank arm 533 and bevel gear 515 have been
pivoted further clockwise. This rotates the steering disc 513 and
steering column 514 to rotate further to the right and also causes
the torque links 511, 512 to change the direction of the wheel 502
so that it is being steered in a right direction.
[0062] Hence, the steering direction of the wheel 502 can be
controlled by the actuator 530 when in the "weight on wheel"
situation.
[0063] FIG. 5 shows a perspective view of the centreing cam
arrangement 542 of the aircraft nose landing gear 500 in a "weight
on wheel" situation. The centreing cam arrangement is designed to
do two things. Firstly, when there is a "weight off wheel"
situation, the arrangement 542 ensures that the wheel 502 is
orientated in a central orientation. This means that when the
aircraft lands so that the wheel 502 controls the direction of the
aircraft, the aircraft will not be steered off course by a wheel
that is being orientated significantly left or right. This is
achieved by the wheel strut 541 sliding downwards in relation to
the steering column 514 when in a "weight off wheel" situation.
This causes an internal downwardly facing notch 544 in the wheel
strut 541 to fall into a corresponding internal upwardly facing
groove 543 of the steering column 514. It is also noted that each
of the notch and groove 544, 543 have corresponding tapered sides
546, 545 to effect rotation of the steering column 514 (and
therefore wheel 502) as the notch 544 and groove 543 line up.
[0064] Secondly, also when there is a "weight off wheel" situation,
the arrangement 542 (and in particular, the notch 544 in groove
543) rotationally fixes the steering column 514 in relation to the
wheel strut 541 so that the steering column 514 cannot rotate. This
means that the steering disc 513, bevel gear 515 and crank arm 533
also cannot rotate. Hence, when in a "weight off wheel" situation,
lengthening and shortening of the lever arm 532 does not cause
rotation of the crank arm 533, but instead causes the landing gear
leg 501 to be pulled on by the lever arm 532 (via crank arm 533) so
that it pivots about pivot point 506 to pivot the leg 501 in a
stowing direction 702, as shown in FIG. 3.
[0065] In order for this to happen, the uplock actuator has to also
be actuated to move the uplock "over-centre" so that the two parts
523, 524 of the uplock can collapse and allow the two parts of the
drag strut 521, 522 to also collapse, as shown in FIG. 3.
[0066] FIGS. 6a and 6b show side views of part of an aircraft nose
landing gear 600 according to a second embodiment of the invention.
Here, corresponding similar elements to the first embodiment (which
are not described again for efficiency) are labelled with a
preceding "6" instead of a "5". In this second embodiment, the
wheel strut 641 is provided at an upper end with a downwardly
pointing triangular member 680. When in the "weight on wheel"
situation of FIG. 6a, the wheel strut 641 has been slid upwards in
relation to the steering column 614 and hence triangular member 680
is above the bevel gear 615 and does not affect its ability to
rotate. However, when in the "weight off wheel" situation of FIG.
6b, the wheel strut 641 has been slid downwards in relation to the
steering column 614 and hence triangular member 680 is adjacent to
the bevel gear 615. In fact, the point of the triangle lodges in
between two projections (not shown) on the edge of the bevel gear
615 and prevent its rotation. Hence, the triangular member 680 is
used to lock the bevel gear 615, steering disc 613 and steering
column 614 and prevent their rotation when in the "weight off
wheel" situation. This ensures that actuation of the actuator 630
would cause deployment/stowage of the landing gear 60, rather than
steering of the wheel 602, in a similar way to the centreing cam
arrangement 542 of the first embodiment.
[0067] FIG. 7 shows a front view of an aircraft 1000. The aircraft
1000 comprises a fuselage 100, two wings 210, 202 (each with one
underwing engine) and a tailplane 300. Each of the wings 201, 202
is also provided with a main landing gear 401, 402. Finally, the
aircraft 1000 is fitted with a nose landing gear according to
either the first 500 or the second 600 embodiment.
[0068] Whilst the present invention has been described and
illustrated with reference to particular embodiments, it will be
appreciated by those of ordinary skill in the art that the
invention lends itself to many different variations not
specifically illustrated herein. By way of example only, certain
possible variations will now be described.
[0069] The landing gear may be provided with two ways of
rotationally fixing the steering column 514, 615; one way using a
notch 544 of the centreing cam arrangement 542 of FIG. 5 and
another way of using a triangular member 680 as shown in FIGS. 6a
and 6b.
[0070] The aircraft landing gear 500, 600 may comprise more than
one wheel 502, 602.
[0071] The aircraft landing gear 500, 600 may be a nose landing
gear or any other landing gear.
[0072] Any aircraft may be used with this invention, and not just
(a particularly sized) commercial passenger airliner, as shown in
FIG. 7.
[0073] Where in the foregoing description, integers or elements are
mentioned which have known, obvious or foreseeable equivalents,
then such equivalents are herein incorporated as if individually
set forth. Reference should be made to the claims for determining
the true scope of the present invention, which should be construed
so as to encompass any such equivalents. It will also be
appreciated by the reader that integers or features of the
invention that are described as preferable, advantageous,
convenient or the like are optional and do not limit the scope of
the independent claims. Moreover, it is to be understood that such
optional integers or features, whilst of possible benefit in some
embodiments of the invention, may not be desirable, and may
therefore be absent, in other embodiments.
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